body{
  display: flex;
  align-items: center;
  position: relative;
  height: 100vh;
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
  transition: background 1s ease;
}

body::before{
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  height: 100%;
  width: 100%;
  background-color: rgba(0, 0, 0, .7);
}

#app{
  position: relative;
  z-index: 3;
  width: 1000px;
  margin: 0 auto;
  height: 600px;
}

.container{
  width: 100%;
  height: 100%;
  overflow: hidden;
}

.img_list{
  width: 1000%;
  height: 100%;
  border-radius: 10px;
  box-shadow: 0 1px 10px #ccc;
  transition: transform 1s ease-out;

}



.img_list .img{
  float: left;
  width: 1000px;
  height: 100%;
  background-image: url(https://images.unsplash.com/photo-1549880338-65ddcdfd017b?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=2100&q=80);
  background-repeat: no-repeat;
  background-position: center;
  background-size: cover;
}

.arrow_box{
  display: flex;
  justify-content: center;
  align-items: center;
  position: absolute;
  width: 80px;
  height: 80px;
  top: 50%;
  transform: translateY(-50%);
  border: 1px solid #fff;
  cursor: pointer;
  z-index: 33;
}

.arrow_box:active .arrow{
  transform: scale(.9);
}

.prev{
  left: -80px;
  border-right: 0;
}

.next{
  right: -80px;
  border-left: 0;
}

.arrow{
  width: 50px;
  height: 50px;
  transition: transform .3s linear;
}

.dot{
  display: flex;
  position: absolute;
  bottom: 10px;
  left:50%;
  transform: translateX(-50%);
  width: auto;
}

.dot_item{
  width: 10px;
  height: 10px;
  background-color: rgba(0, 0, 0, .3);
  margin-right: 10px;
  border-radius: 50%;
  transition: width 1s linear;
}

.dot_item.active{
  background-color: #fff;
  width: 30px;
  border-radius: 5px;
}